• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 2 answers
  • Subscribers 51 subscribers
  • Views 353 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

CC2564CSTBTBLESW: [HID + SPPLE] Noise occurs when inquiry.

Kevin Lam61
Prodigy 240 points
Part Number: CC2564CSTBTBLESW
Other Parts Discussed in Thread: CC2564C

Hi,

I got a similar issue as below thread. Noise occurs when inquiry. I must combine two profile together in my project, so any solution for this resource issue on STM32 SDK version 4.2.1.1?

Thanks and regards,

Kevin

  • 0
    TI__Mastermind 29291 points

    Hi Kevin,

    Could you please explain the "noise" in your case? If you are combining HFP and SPPLE, how are you experiencing the noise? None of these two profiles have audio or voice capabilities.

    Best regards,

    Vihang

  • 0 in reply to Vihang Parmar
    Prodigy 240 points

    Hi Vihang,

    I combined HID Demo code and SPPLE Demo code in my project, both are working perfectly after initialization. The noise was generated when calling "Inquiry" in HIDDemo.c followed the default setting as below:

    ret_val = GAP_Perform_Inquiry(BluetoothStackID, itGeneralInquiry, 0, 0, 10, MAX_INQUIRY_RESULTS, GAP_Event_Callback, 0);

    The noise is hearable and it is around the chip, once "Inquiry" completed, the noise was gone. And we also noticed that when calling Inquiry, the current consumption goes up to 4XmA but normally it just drains 1XmA during advertising.

    You are correct, none of these two profiles have audio or voice capabilities, but unfortunately, our device has to connect with a speaker for sound playback and the noise is coupled and amplified during sound playback. Even we don't connect with the speaker, the noise still can be heard if put the ears close to the chip, we are not sure that the noise is coming from the components around the chip (followed the reference circuit) or it is coming from the chip itself.

    So, we would like to know what action will take in the chip if running "Inquiry" and please let us know if any possibility to induce this noise.

    Thanks and regards,

    Kevin

  • 0 in reply to Kevin Lam61
    TI__Mastermind 29291 points

    Kevin,

    Kevin Lam61 said:
    The noise is hearable and it is around the chip, once "Inquiry" completed, the noise was gone. And we also noticed that when calling Inquiry, the current consumption goes up to 4XmA but normally it just drains 1XmA during advertising.

    This ringing problem seems like a hardware issue. Most likely in the board level design and or power supply design, since the issue occurs when the CC2564C's current consumption gets higher in certain operational modes. To be clear, the higher current consumption is expected in inquiry mode compared to some of the low power activities like LE advertisements at larger intervals. This issue does not seem to be related to the CC2564C or the higher level software (e.g. HID or SPPLE profiles) running on the host. You will need to debug your hardware design in order to find out the root cause of this issue.

    First of all, you may want to examine the power supply on your hardware. Additionally, you can try to run the Continuos TX test on CC2564C (VS_Enable_FCC_Test_Mode) that has expected current consumption of >100mA. This may make it more apparent to debug the hardware under high current consumption. 

    Best regards,

    Vihang

  • 0 in reply to Vihang Parmar
    Prodigy 240 points

    Hi Vihang,

    Thanks for your suggestion, we are going to debug the hardware design now, will close the thread once figure out the root cause.

    Best regards,

    Kevin

  • 0 in reply to Kevin Lam61
    Prodigy 240 points

    Hi Vihang,

    We believe that the noise is induced by the capacitors that connect with 3.3V of STM32F401, because after replacing the capacitors can reduce the noise a little bit. Do you know what exactly the stack is doing during "Inquiry" period?

    Thanks and regards

    Kevin

  • 0 in reply to Kevin Lam61
    TI__Mastermind 29291 points

    Kevin,

    Kevin Lam61 said:
    Do you know what exactly the stack is doing during "Inquiry" period?

    The answer really depends on your overall application running on the host (STM32). As far as the inquiry is concerned, the host starts the inquiry by sending an HCI command to the CC2564C controller. Rest of the inquiry process is internal to the CC2564C controller. As soon as the controller "finds" a remote device in the inquiry, it will send an HCI event to the host. At a high level, those are the transactions between the host and the controller during inquiry. If the host is only doing inquiry, the stack running on the host is not supposed to do much else.

    However, if you have some sleep of low power mode implemented in your system, that is something you may want to look into. Since the host stack does not have much to do once the inquiry starts, besides reactively receiving the events from the controller, it may enter a low power state if it is configured (this is typically outside the BT stack at the MCU level). If the host is entering and exiting the low power state frequently, that can be causing the behavior on the power lines and/or on the bypass capacitor as you observed. Hope this helps in your debug.

    Best regards,

    Vihang

  • 0 in reply to Vihang Parmar
    Prodigy 240 points

    Vihang,

    Thanks for the explanation.

    We figure it out that the noise is coming from host MCU (STM32) VDD, and resolved by changing the capacitor value and adding RC filter.

    Thank you very much,

    Kevin